Most lamps for a vehicle such as, for example, a car, have adopted a configuration in which a light source unit is equipped within a lamp housing, which is configured with a lamp body and a light transmitting member such as, for example, a lens or a light transmitting cover, and light emitted from the light source unit is directed to the light transmitting member. Recently, in order to respond to the diversification of designs of vehicle lamps, the shapes of the lamp housing and the light transmitting member have become complicated, and thus, a light source unit has been proposed which has a stepped configuration in which light emitting elements are arranged at positions of which the optical axis directions are different from each other.
For example, Japanese Patent Laid-Open Publication No. 2013-232305 proposes a light source unit in which a flexible printed circuit board (FPC), on which a plurality of light emitting elements is mounted, is bent stepwise in a thickness direction and equipped in a lamp housing, and the FPC is fixedly supported on a base member placed within the lamp housing. Therefore, with the light source unit, it is difficult to bend the FPC into a predetermined state to be fixedly supported on the base member. It is also difficult to set a light distribution characteristic of a lamp with high precision by aligning the optical axes of the light emitting elements mounted on the FPC with an optical axis direction of the lamp.
A light source unit using, instead of the FPC, a resin molded article with a circuit pattern formed on a surface thereof by, for example, plating, has been considered in order to improve the light distribution characteristic of the light source unit having the FPC configuration described above. For example, Japanese Patent Laid-Open Publication No. 2014-213570 proposes such a resin molded article that is formed by performing injection-molding using a special resin that is obtained by hybridizing a metal complex and a base resin, irradiating laser light to a portion of the obtained resign molded article to enhance the catalyst activity of the metal complex, and forming an electroless plating film only on the portion irradiated with the laser light. Such a resin molded article obtained by combining a circuit pattern and a resin structure is also referred to as a molded interconnect device (MID).